FOVMath

IMX533 square-sensor cameras: what a 1:1 frame changes for framing

The IMX533 records a square 11.31 × 11.31 mm frame of 3.76 µm pixels. A circle fills 78.5 % of a square but only 52.4 % of a 3:2 frame, and a square looks the same after a 90° turn, so round nebulae and clusters frame with little wasted area and no landscape-or-portrait decision. ZWO, Player One and ToupTek publish 3008 × 3008 pixels; QHY publishes only a 3008 × 3028 total area.

Published October 15, 2026 . Sources are listed at the end of the page.

IMX533 square cameras: published specifications
Model Sensor Type Resolution (px) Pixel (µm) Sensor (mm) ADC bits Full well (ke⁻) Read noise (e⁻) Cooling
ZWO ASI533MC Pro Sony IMX533 Colour, cooled 3008 × 3008 3.76 11.31 × 11.31 14 50 1.0–3.8 2-stage TEC; product table: 35 ℃; manual: 30–35 °C below ambient (at 30 °C ambient)
ZWO ASI533MM Pro Sony IMX533 Mono, cooled 3008 × 3008 3.76 11.31 × 11.31 14 50 1.0–3.8 2-stage TEC; product table: 35 ℃; manual: 30–35 °C below ambient
QHYCCD QHY533M Sony IMX533 Mono, cooled 3008 × 3028 3.76 11.3 × 11.4 † 14 58 1.3–3.4 Dual-stage TEC; long exposures (>1 s) typically 35 °C below ambient, short exposures (<1 s) typically 30 °C below ambient (test ambient +20 °C)
QHYCCD QHY533C Sony IMX533 Colour, cooled 3008 × 3028 3.76 11.3 × 11.4 † 14 58 1.3–3.4 Dual-stage TEC; long exposures (>1 s) typically 35 °C below ambient, short exposures (<1 s) typically 30 °C below ambient (test ambient +20 °C)
Player One Ares-C Pro Sony IMX533 Colour, cooled 3008 × 3008 3.76 11.31 × 11.31 14 73 4.46-1e 35°C-40°C below ambient (2-stage TEC)
Player One Ares-M Pro Sony IMX533 Mono, cooled 3008 × 3008 3.76 11.31 × 11.31 14 73 4.46-1e 35°C-40°C below ambient (2-stage TEC)
Player One Saturn-C SQR Sony IMX533 Colour, uncooled 3008 × 3008 3.76 11.31 × 11.31 14 73 4.46-1e None
Player One Saturn-M SQR Sony IMX533 Mono, uncooled 3008 × 3008 3.76 11.31 × 11.31 14 73 4.46-1e None
ToupTek ATR533C Sony IMX533 Colour, cooled 3008 × 3008 3.76 11.31 × 11.28 14 50 1.1 e- (HCG mode) Two-stage TEC, up to 42°C below ambient
ToupTek ATR533M Sony IMX533 Mono, cooled 3008 × 3008 3.76 11.31 × 11.28 14 52 1.1e- (HCG mode) Two-stage TEC, up to 42°C below ambient

† Computed as pixels × pixel size; the manufacturer gives no sensor size in millimetres.

Most astronomy sensors are 3:2 or 16:9 rectangles. The IMX533 is square: 3008 × 3008 pixels of 3.76 µm make an 11.31 mm square with a 16.0 mm diagonal. Ten cameras in our data use it, cooled and uncooled, from ZWO, QHY, Player One and ToupTek. Their fields are the same; this page is about what the shape does for framing.

A square wastes less sky around round targets

The largest circle that fits any frame is limited by its shorter side. Its share of the frame is a fixed ratio:

area of inscribed circle ÷ frame area = π/4 × (short side ÷ long side)

For a square that is 78.5 %. For the IMX571’s 6248 × 4176 frame it is 52.5 %, and for the 16:9 IMX585 it is 44.2 %. Put differently, a round nebula sized to the short side leaves 21.5 % of a square frame as surrounding sky, against about 47.5 % on an APS-C frame of that aspect ratio. The square does not frame bigger round objects than APS-C, because the IMX571’s short side, 15.70 mm, is still longer. It frames them with less empty frame and fewer pixels to store and process: 9.05 MP against 26.09 MP.

A worked example: the Rosette Nebula is 100′ across in the Sharpless catalogue. An IMX533’s side spans exactly 100′ at 389 mm; an IMX571’s short side does so at 540 mm. Shorter focal lengths leave margin, which the target framing calculator adds for you. The Rosette page shows the object against real setups.

Orientation stops being a decision

A square looks the same after a 90° turn, so there is no landscape or portrait choice. Rotation still matters for elongated targets, but in a different way: the longest line on the frame is the diagonal, √2 times the side. At 1000 mm the side spans 38.9′ and the diagonal 55.0′, so a thin galaxy laid along the diagonal gets 41 % more length than one laid along an edge. For mosaics, the mosaic planner normally tests both sensor orientations; with a square sensor the two results are identical, which also makes panel overlap the same on every edge.

Where the published numbers differ

ZWO, Player One and ToupTek publish 3008 × 3008 pixels. QHY publishes only a total pixel area of 3008 × 3028 that it says includes optical-black and overscan rows, along with “9 Megapixels” effective. Our tables compute from what is published, so the QHY533 rows are 0.075 mm (0.66 %) taller: 39.1′ instead of 38.9′ at 1000 mm. That difference reflects QHY’s labeling, not a taller sensor. ToupTek’s ATR533 pages give the image area as 11.31 × 11.28 mm, slightly short of the 11.31 mm that 3008 square pixels of 3.76 µm compute to.

The other published specs vary more than the field does:

  • Full well: ZWO 50 ke⁻, QHY 58 ke⁻, Player One 73 ke⁻, ToupTek 50 ke⁻ (ATR533C) and 52 ke⁻ (ATR533M). All are listed with a 14-bit ADC.
  • Back focus: ZWO lists the pair 17.5/6.5 mm; QHY 14 mm for the QHY533M and 17 mm for the QHY533C; Player One 17.5 mm for the cooled Ares Pro and 12.5 mm for the uncooled Saturn SQR; ToupTek 17.5 mm.
  • Cooling: from none on the Saturn SQR to “up to 42 °C” on the ToupTek ATR533 pages.

The uncooled square option

Player One’s Saturn-C SQR and Saturn-M SQR put the same sensor in an uncooled body. Player One files the Saturn-C SQR as a planetary camera and markets it for Moon and Sun mosaics as well as lucky imaging of deep-sky objects; an external fan is optional. For lunar mosaics, the square shape means a panel plan still holds if the camera ends up turned by 90° on the focuser. The Player One family page compares it with the cooled Ares Pro.

Field of view and image scale at common focal lengths

Computed for each camera from its published pixel count and pixel size (or its published sensor size), using the exact arctan formula. Each cell shows width × height and the image scale in arcseconds per pixel.

IMX533 square cameras: field of view by focal length
Camera 250 mm400 mm600 mm1000 mm2000 mm
ZWO ASI533MC Pro 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
ZWO ASI533MM Pro 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
QHYCCD QHY533M 2.59° × 2.61° 3.10″/px 97′ × 98′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 20′ 0.39″/px
QHYCCD QHY533C 2.59° × 2.61° 3.10″/px 97′ × 98′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 20′ 0.39″/px
Player One Ares-C Pro 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
Player One Ares-M Pro 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
Player One Saturn-C SQR 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
Player One Saturn-M SQR 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
ToupTek ATR533C 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px
ToupTek ATR533M 2.59° × 2.59° 3.10″/px 97′ × 97′ 1.94″/px 65′ × 65′ 1.29″/px 39′ × 39′ 0.78″/px 19′ × 19′ 0.39″/px

Check your own optics with the field of view calculator or the sampling calculator; both list these cameras as presets.

Questions

Does a square sensor frame round objects bigger than an APS-C sensor?
No. The largest circle fits the shorter side, which is 11.31 mm on the IMX533 and 15.70 mm on the APS-C IMX571. The square's advantage is that less of the frame lies outside the circle: 21.5 % instead of about 47.5 %.
Is the uncooled Player One Saturn SQR the same field as the cooled cameras?
Yes. It lists the same 3008 × 3008 pixels at 3.76 µm, so its field matches the Ares Pro and the ZWO and ToupTek cooled IMX533 bodies exactly. Player One lists it as a planetary camera, with passive cooling and a 12.5 mm back focus.
  • IMX571 APS-C cameras Eleven cameras on Sony's IMX571: the same 3.76 µm pixels and near-identical fields, with differences in published cooling, back focus, full well and read noise.
  • Player One cameras Player One's Poseidon, Ares, Zeus, Uranus, Saturn, Neptune, Mars, Ceres and Apollo cameras mapped to their Sony sensors, with cooled and uncooled twins compared.
  • QHYCCD cooled cameras QHY's cooled cameras from the QHY183 to the QHY600, with sensor sizes computed from pixels × pitch, effective vs total pixel areas, and two discontinued models.
  • Target framing Check whether a galaxy or nebula fits your sensor, with catalogue sizes and position angles, a star-chart preview and the focal length for a chosen fill.
  • Mosaic planner Count mosaic panels for a nebula or galaxy from your sensor, focal length and overlap, with both camera orientations tried and a panel layout chart.
  • Rosette Nebula The Rosette spans 100′ in the Sharpless catalogue, with the cluster NGC 2244 at its centre. Focal lengths for APS-C, full frame and square sensors.

Sources

References for the text first, then the manufacturer specification page for each camera in the tables.

  1. Catalogue of H II Regions (Sharpless 1959), VII/20: Sh2-275 CDS VizieR. Diameter 100 arcmin. Accessed October 12, 2026.
  2. ZWO ASI533MC Pro specifications ZWO. Accessed October 12, 2026.
  3. QHYCCD QHY533M specifications QHYCCD. Accessed October 12, 2026.
  4. Player One Ares-C Pro specifications Player One. Accessed October 12, 2026.
  5. Player One Ares-M Pro specifications Player One. Accessed October 12, 2026.
  6. Player One Saturn-C SQR specifications Player One. Accessed October 12, 2026.
  7. Player One Saturn-M SQR specifications Player One. Accessed October 12, 2026.
  8. ToupTek ATR533C specifications ToupTek. Accessed October 12, 2026.
  9. ToupTek ATR533M specifications ToupTek. Accessed October 12, 2026.